ABSTRACT:A simple, accurate, precise, rapid and sensitive reverse phase high performance liquid chromatography (RP-HPLC) method has been developed for the estimation of Simvastatin and Niacin in Pure and Tablet dosage forms. Inertsil ODS, RP-18 Column (250 x 4.6 mm ID, 5µ) was used with a mobile phase containing a mixture of Phosphate buffer pH 2.5, Methanol and Acetonitrile in the ratio of 45:20:35. The procedure was carried out at pH-3.5. The compounds were eluted at a flow rate of 1.0 ml/min. results were determined at 220 nm with fixed wavelength PDA detector. The linearity for Niacin was found between 75-175 µg/ml and between 3-7 µg/ml for Simvastatin. The retention times were found as 4.747 min and 2.970min for Niacin and Simvastatin respectively. The above method was validated in terms of System suitability, linearity, accuracy, precision, Limit of Detection (LOD), Limit of Quantification (LOQ), Robustness in accordance with ICH guidelines. The method was rapid, simple, economical and suitable for routine quality control analysis.